Methods for random access in radio nodes and user equipment

ABSTRACT

The present disclosure relates to a method used in a radio node and the associated radio node. The method comprises: obtaining a network geometry of a User Equipment (UE) served by the radio node with respect to a coverage served by the radio node; determining a carrier sensing threshold for the UE based on the network geometry, the carrier sensing threshold for use in Listen-Before-Talk (LBT) measurement over a radio frequency band applicable for transmitting data to the UE; and applying the carrier sensing threshold in the LBT measurement. The present disclosure also relates to a method used in a UE and the associated UE, and to a method used in a radio node and the associated radio node.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National stage of International Application No.PCT/CN2015/086643, filed Aug. 11, 2015, which is hereby incorporated byreference.

TECHNICAL FIELD

The present disclosure generally relates to the technical field ofwireless communications, and particularly, to a method used in a radionode and the associated radio node, to a method used in a User Equipment(UE) and the associated UE, and to a method used in another radio nodeand the associated radio node.

BACKGROUND

This section is intended to provide a background to the variousembodiments of the technology described in this disclosure. Thedescription in this section may include concepts that could be pursued,but are not necessarily ones that have been previously conceived orpursued. Therefore, unless otherwise indicated herein, what is describedin this section is not prior art to the description and/or claims ofthis disclosure and is not admitted to be prior art by the mereinclusion in this section.

Owing to the increasing demand to enhance wireless capacity and the lackof availability of spectrum in the lower frequency range (e.g., from 800MHz to 3 GHz), the use of frequencies in tens of GHz is beinginvestigated. Investigations explore the high frequency bands, forinstance, in the frequencies of 6 GHz, 30 GHz, 60 GHz and 98 GHz for thefuture mobile networks, e.g., the 5th Generation (5G) networks. At suchfrequencies, a very large bandwidth of radio frequency band isavailable. This means both operating frequency and bandwidth for the 5Gnetworks are much higher than those used in the legacy mobile networke.g., the 3rd Generation (3G) and the 4th Generation (4G) networks.However, due to the large signal attenuation with respect to path loss,a network operating over such high frequencies is supposed to coversmall areas with densely deployed radio access nodes (ANs). Such adeployment may provide sufficient coverage for indoor/hot areas.

FIG. 1 schematically shows one example of the future mobile networks. Asshown in FIG. 1, there is a network node or a control node called asCentral Control Unit (CCU), which is responsible for parameterconfigurations and coordination among ANs or Access Points (APs), e.g.,AN1, AN2, AN3, and AN4, or any other radio nodes that enable of coveringa certain geographical area (similarly corresponds to a cell in the 3Gor 4G). Each AN can serve one or more communication devices, such asUser Equipments (UE), operating in the wireless communication networksor systems, also known as e.g., wireless terminals, mobile terminalsand/or mobile stations and the like terminal devices. For example, AN1serves UE1, and AN2 serves UE2, etc.

Spectrum sharing is an important characteristic of the future mobilenetworks. In order to improve the frequency resource utilization,spectrum sharing may be one important method in the future mobilenetworks compared to the mainly dedicated frequency resource allocationin the current 3G or 4G networks. Via spectrum sharing, each co-existingnetwork can have the opportunity to use the whole shared spectrum whenit has traffic and other co-existing network does not have traffic.Thereby, both the spectrum utilization efficiency and user experiencecan be clearly improved, compared to simply dividing the whole spectruminto multiple segments and assigning one spectrum segment to eachindividual network as dedicate frequency resource.

Considering the applicability of spectrum sharing in radio access forthe future mobile networks and the inherited benefits of thecontention-based radio resource allocation (e.g., higher flexibility andrelative lower complexity), contention-based Medium Access Control (MAC)seems promising and may probably be used in the future mobile networksin combination with scheduling based method(s).

As one contention-based radio resource allocation scheme, thecontention-based MAC works in a distributed way, where radio resourceassignments are decided for each link pair separately. As a schemesimilarly as IEEE 802.11, in order to avoid collision, a node whichneeds radio resource shall send a contention message to claim forresource according to predefined rules. The resource reservation issuccessful if a peer node accepts the reservation. The contention-basedMAC works well when low coordination between cells is needed and is alow complexity solution to allow a diversity of link types. It is wellknown that contention based MACs are suffering high performance losseswhen heavy loads are in the system if certain coordination orsituational parameter adjustment is not available.

The Listen Before Talk (LTB) operating procedure in IEEE 802.11 is onemost well-known contention-based MAC protocol. According to LBT, whenthere is data traffic for a link, the link's transmitter shall firstlylisten to or sense corresponding radio resources (e.g., a radiofrequency band corresponding to the link, also called as channel) todetermine availability of the channel based on the received power overthe channel. If the channel is determined to be available, thetransmitter can take the channel by starting the data transmission overthe channel directly or by using Request To Send (RTS)-Clear To Send(CTS) mechanism.

In the context of the 5G system, further enhancement of acontention-based method is necessary to boost its performance such as asuperior and stable Quality of Service (QoS), spectrum efficiency. TheLong-Term Evolution (LTE) network usually owns good networkcontrollability by a good network dimension and well defined networkcontrolling functionality, how to optimize the contention based radioresource allocation in 5G scenarios remains as an open issue.

SUMMARY

The contention-based radio resource allocation usually utilizes thesensing at all transmitter-sides, but usually neither considers theimpact of the UE's location (e.g., the UE is located in the center ofcell or in the edge of cell) nor considers the impact of high-gainbeamforming. This may cause inefficient use of the frequency resource.

It is in view of at least one of the above considerations and othersthat the various embodiments of the present technology have been made.The present disclosure proposes to optimize the contention-based radioresource allocation based on the geometry of the radio nodes.

According to a first aspect of the present disclosure, there is provideda method used in a radio node. The method includes: obtaining a networkgeometry of a UE served by the radio node with respect to a coverageserved by the radio node; determining a carrier sensing threshold forthe UE based on the network geometry, the carrier sensing threshold foruse in Listen-Before-Talk (LBT) measurement over a radio frequency bandapplicable for transmitting data to the UE; and applying the carriersensing threshold in the LBT measurement.

In an embodiment, applying the threshold in the LBT measurementincludes: measuring a radio frequency signal power level on the radiofrequency band; and determining that the radio frequency band isavailable for transmitting data to the UE if the radio frequency signalpower level is smaller than or equal to the carrier sensing threshold.In this embodiment, the method further includes: transmitting data tothe UE over the radio frequency band.

In an embodiment, the network geometry includes location of the UE inthe coverage.

In an embodiment, determining the carrier sensing threshold for the UEbased on the network geometry includes: adjusting the carrier sensingthreshold to be larger if the UE moves towards the center of thecoverage; and/or adjusting the carrier sensing threshold to be smallerif the UE moves towards the edge of the coverage.

In an embodiment, the location of the UE in the coverage ischaracterized by a pilot signal quality of the radio node.

In an embodiment, the pilot signal quality of the radio node isindicated by one of: a reference signal strength of the radio node; areference signal Signal to Interference plus Noise Ratio (SINR) of theradio node; or a reference signal strength of the radio node andreference signal strength of one or more neighboring radio nodes of theradio node.

According to a second aspect of the present disclosure, there isprovided a method used in a UE served by a radio node. The methodincludes: obtaining a network geometry of the UE with respect to acoverage served by the radio node; determining a carrier sensingthreshold for the UE based on the network geometry, the carrier sensingthreshold for use in Listen-Before-Talk (LBT) measurement over a radiofrequency band applicable for transmitting data to the radio node; andapplying the carrier sensing threshold in the LBT measurement.

According to a third aspect of the present disclosure, there is provideda method used in a radio node. The method includes: obtaining a networkgeometry of a UE served by the radio node with respect to a coverageserved by the radio node; determining a width of a RX beam based on thenetwork geometry, the RX beam for use in Listen-Before-Talk (LBT)measurement over a radio frequency band applicable for transmitting datato the UE; and applying the RX beam with the determined width in the LBTmeasurement.

According to a fourth aspect of the present disclosure, there isprovided a radio node. The radio node includes an obtaining unitconfigured to obtain a network geometry of a UE served by the radio nodewith respect to a coverage served by the radio node. The radio nodefurther includes a determining unit configured to determine a carriersensing threshold for the UE based on the network geometry, the carriersensing threshold for use in Listen-Before-Talk (LBT) measurement over aradio frequency band applicable for transmitting data to the UE. Theradio node further includes a LBT measurement unit configured to applythe carrier sensing threshold in the LBT measurement.

According to a fifth aspect of the present disclosure, there is provideda radio node. The radio node includes a transceiver, a processor and amemory. The memory contains instructions executable by the processorwhereby the radio node is operative to: obtain a network geometry of aUE served by the radio node with respect to a coverage served by theradio node; determine a carrier sensing threshold for the UE based onthe network geometry, the carrier sensing threshold for use inListen-Before-Talk (LBT) measurement over a radio frequency bandapplicable for transmitting data to the UE; and apply the carriersensing threshold in the LBT measurement.

According to a sixth aspect of the present disclosure, there is provideda UE served by a radio node. The UE includes an obtaining unitconfigured to obtain a network geometry of the UE with respect to acoverage served by the radio node.

The UE further includes a determining unit configured to determine acarrier sensing threshold for the UE based on the network geometry, thecarrier sensing threshold for use in Listen-Before-Talk (LBT)measurement over a radio frequency band applicable for transmitting datato the radio node. The UE further includes a LBT measurement unitconfigured to apply the carrier sensing threshold in the LBTmeasurement.

According to a seventh aspect of the present disclosure, there isprovided a UE served by a radio node. The UE includes a transceiver, aprocessor and a memory. The memory contains instructions executable bythe processor whereby the UE is operative to: obtain a network geometryof the UE with respect to a coverage served by the radio node; determinea carrier sensing threshold for the UE based on the network geometry,the carrier sensing threshold for use in Listen-Before-Talk (LBT)measurement over a radio frequency band applicable for transmitting datato the radio node; and apply the carrier sensing threshold in the LBTmeasurement.

According to an eighth aspect of the present disclosure, there isprovide a radio node. The radio node includes an obtaining unitconfigured to obtain a network geometry of a UE served by the radio nodewith respect to a coverage served by the radio node. The radio nodefurther includes a determining unit configured to determine a width of aRX beam based on the network geometry. The RX beam is used inListen-Before-Talk (LBT) measurement over a radio frequency bandapplicable for transmitting data to the UE. The radio node furtherincludes a LBT measurement unit configured to apply the RX beam with thedetermined width in the LBT measurement.

According to a ninth aspect of the present disclosure, there is provideda radio node. The radio node includes a transceiver, a processor and amemory. The memory contains instructions executable by the processorwhereby the radio node is operative to: obtain a network geometry of aUE served by the radio node with respect to a coverage served by theradio node; determine a width of a RX beam based on the networkgeometry, the RX beam for use in Listen-Before-Talk (LBT) measurementover a radio frequency band applicable for transmitting data to the UE;and apply the RX beam with the determined width in the LBT measurement.

According to a tenth aspect of the present disclosure, there is provideda computer program product storing instructions that when executed,causing one or more computing devices to perform the method according toany one of the first to the third aspects.

The above embodiments of the first aspect are also applicable for theremaining aspects.

According to the 1^(st), 2^(nd), 4^(th)-7^(th), and 10^(th) embodimentsof the present disclosure, the network geometry is considered in settinga threshold for use in determining whether a radio frequency band isapplicable for transmitting data from a radio node to a UE served by theradio node or from the UE to the radio node. For example, for a UElocated in the center of its serving radio node, the higher thresholdmay be set, compared to a UE located in the edge of the radio node. Thiscan improve channel reusing in the contention-based resource allocation.

According to the 3^(rd), 8^(th), 9^(th) and 10^(th) embodiments of thepresent disclosure, the network geometry is considered in setting a RXbeam for use in a radio node listening to a radio frequency band isapplicable for transmitting data to a UE served by the radio node. Forexample, for a UE located in the center of its serving radio node, thecorresponding RX beam to be applied by the radio node is larger,compared to a UE located in the edge of the radio node. This can relievethe deafness problem caused by the high gain beamforming, which may bepopular in the further mobile networks.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of this disclosure will become morefully apparent from the following description and appended claims, takenin conjunction with the accompanying drawings. Understanding that thesedrawings depict only several embodiments in accordance with thedisclosure and are, therefore, not to be considered limiting of itsscope, the disclosure will be described with additional specificity anddetail through use of the accompanying drawings.

FIG. 1 schematically shows one example of the future mobile networks.

FIG. 2 illustrates an exemplary scenario showing one concept of thepresent disclosure.

FIGS. 3-4 schematically illustrate a method 300 used in a radio nodeaccording to embodiments of the present disclosure.

FIG. 5 illustrates one exemplary scenario showing how to adapt carriersensing thresholds based on the network geometry according toembodiments of the present disclosure.

FIGS. 6-7 schematically illustrate a method 600 used in a UE accordingto embodiments of the present disclosure.

FIG. 8 illustrates exemplary wireless systems in which high gainbeamforming is applied.

FIGS. 9-10 schematically illustrate a method 900 used in a radio nodeaccording to embodiments of the present disclosure.

FIG. 11 illustrates one exemplary scenario showing how to adapt RX beamsbased on the network geometry according to embodiments of the presentdisclosure.

FIG. 12 is a schematic block diagram of a radio node 1200 according toembodiments of the present disclosure.

FIG. 13 is a schematic block diagram of a UE 1300 according toembodiments of the present disclosure.

FIG. 14 is a schematic block diagram of a radio node 1400 according toembodiments of the present disclosure.

FIG. 15 schematically shows an embodiment of an arrangement 1500comprising at least one particular computer program product 1508according to a particular embodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, the present disclosure is described with reference toembodiments shown in the attached drawings. However, it is to beunderstood that those descriptions are just provided for illustrativepurpose, rather than limiting the present disclosure. Further, in thefollowing, descriptions of known structures and techniques are omittedso as not to unnecessarily obscure the concept of the presentdisclosure.

According to Listen-before-talk (LBT), if a radio node is intended toperform a transmission over a radio frequency band, it is required tosense the radio frequency band for a period of time to determineavailability of the radio frequency band. To be specific, a non-zerothreshold (also called as a carrier sensing threshold) may be used hereto judge the availability of the radio frequency band. The radio nodemay compare a radio frequency signal power level listened over the radiofrequency and with the carrier sensing threshold. If the radio frequencysignal power level is not larger than the carrier sensing threshold, theradio node will determine that the radio frequency band is available andthen commence to perform the transmission. Usually, the operationsbefore the transmission may be called as LBT measurement.

It should be noted that the radio frequency band here refers to achannel, and may be also construed as involving one or more continues ordiscontinues radio sub-bands or sub-carriers.

The present disclosure firstly proposes to adaptively adjust the carriersensing threshold based on a network geometry.

In mathematical modeling of wireless networks, a network geometryusually refers to relative locations of nodes, such as transmitters andreceivers. It is used to represent aspects of network where (forexample, cellular networks) the underlying geometry plays a fundamentalrole due to the interference of other transmitters of differentlocations. For example, for UE1 as shown in FIG. 1, its network geometrymay refer to location of UE1 in the coverage served by AN1. It should benoted that the location here refers either to a geographical location ofthe UE within the coverage, or to a “virtual” location in terms of UE'ssignal quality or strength within the coverage. For example, such alocation may be characterized by a pilot signal quality of AN1. Thepilot signal quality of AN1 is indicated by one of, e.g., a referencesignal strength of AN1; a reference signal SINR of AN1; or a referencesignal strength of AN1 and reference signal strength of one or moreneighboring radio nodes of AN1 (e.g., AN2 or AN3 as shown in FIG. 1).

According to the present disclosure, a relatively lower/higher carriersensing threshold (also called as a RX power threshold) is applied todetermine the channel availability for a link at an AP-coverageedge/center (simply referred to as edge/center herein after). This isbecause that the node close to edge of a cell has a relatively higherprobability to interfere the neighboring-cell radio links (shorterdistance to neighbor cells for UL, and confined elevation BF for DL).Similarly, the node close to the center of a cell has a relatively lowerprobability to interfere the neighboring-cell radio links (largerdistance to neighbor cells for UL). By this way, the channelavailability of the center links can be maximized without a substantialinterference increase to neighbor cells, eventually, the overallspectrum utilization is improved.

FIG. 2 illustrates an exemplary scenario showing one concept of thepresent disclosure.

As shown in FIG. 2, there are two neighboring radio nodes, i.e., AP Aand AP B, and it is assumed that AP A and AP B are deployed in the ceilof a house. UE A1 and UE A2 are both served by AP A, and the former islocated in the center of AP A's coverage and the latter is located inthe edge of AP A's coverage. Similarly, UE B1 and UE B2 are both servedby AP B, and the former is located in the center of AP B's coverage andthe latter is located in the edge of AP B's coverage. It is assumed thatUE A1, UE A2, UE B1 and UE B2 are all deployed in the floor of thehouse. As illustrated, AP A's coverage is partly overlapped with AP B'scoverage.

In such a scenario, Uplink (UL) TX beam/Downlink (DL) TX beam of Link 1from UE A1 to AP A or from AP A to UE A1 reaches the ceil or the floorfirst and only some reflected rays may reach AP B's coverage. Similarly,UL TX beam/DL TX beam of Link 3 from UE B1 to AP B or from AP B to UE B1reaches the ceil or the floor first and only some reflected rays mayreach AP A's coverage. The generated interference from Link 1 to Link 3and Link 4 (AP B-UE B2) can be endurable even though Link 1 transmitssimultaneously with Link 3 or 4. It is similar for Link 3 to transmitsimultaneously with Link 1 or Link 2 (AP A-UE A2).

So, it can be seen that links located in the center of a coverage maygenerate less interference to neighbor links, with compared to linklocated in the edge of the coverage. Hence, it may be beneficial to usea higher carrier sensing threshold for links located in the center ofthe coverage. Considering the coverage depends on the radio node, to putit differently, a higher carrier sensing threshold may be used for UEslocated in the center of the coverage.

FIG. 3 schematically illustrates a method 300 used in a radio nodeaccording to embodiments of the present disclosure. It is assumed thatthe radio node is to transmit data to a UE served by the radio node overa radio frequency band.

At step S310, the radio node obtains a network geometry of the UE withrespect to a coverage served by the radio node. This may be done invarious well-known manners in the art.

In an implementation, the network geometry includes location of the UEin the coverage. Furthermore, the location of the UE in the coverage maybe characterized by a pilot signal quality of the radio node. The pilotsignal quality of the radio node is indicated by one of: a referencesignal strength of the radio node; a reference signal SINR of the radionode; or a reference signal strength of the radio node and referencesignal strength of one or more neighboring radio nodes of the radionode.

For example, when one UE has one or multiple neighboring ANs, therelative geometry may be determined according to the relative qualitydifference between the serving AN and the strongest neighboring AN:L _(R) =P _(rx,A)−max{P _(rx,N1) ,P _(rx,N2) , . . . P _(rx,NX)}where L_(R) is the relative geometry; P_(rx,N1), P_(rx,N2) . . .P_(rx,NX) are the received pilot power from X neighboring ANsrespectively.

At step S320, the radio node determines a carrier sensing threshold forthe UE based on the network geometry. The carrier sensing threshold isused for LBT measurement over the radio frequency band applicable fortransmitting data to the UE.

In an implementation, the carrier sensing threshold may be adjusted tobe larger if the UE moves towards the center of the coverage.Alternatively, the carrier sensing threshold may be adjusted to besmaller if the UE moves towards the edge of the coverage.

At step S330, the radio node applies the carrier sensing threshold inthe LBT measurement.

In an implementation, step S330 may include steps S331, S332, and S333as illustrated in FIG. 4.

At step S331, the radio node measures a radio frequency signal powerlevel on the radio frequency band. Conventionally, before such ameasuring, the radio node may listen to the radio frequency bandperiodically or in a fixed interval.

At step S332, the radio node compares the measured radio frequencysignal power level with the carrier sensing threshold.

If the radio frequency signal power level is smaller than or equal tothe carrier sensing threshold (“Y” branch in FIG. 4), this means thatthe radio frequency band is available currently. Then, the flowchartproceeds to step S333, where the radio node determines that the radiofrequency band is available for transmitting data to the UE. In thiscase, the method 300 proceeds to step S340.

At step S340, the radio node transmits data to the UE over the radiofrequency band.

If the radio frequency signal power level is larger than the carriersensing threshold (“N” branch in FIG. 4), this means that the radiofrequency band is being occupied, e.g., by other radio nodes. In thiscase, the flowchart goes back to step S331 to continue with the LBTmeasurement again.

FIG. 5 illustrates one exemplary scenario showing how to adapt carriersensing thresholds according to the network geometry according toembodiments of the present disclosure.

As shown in FIG. 5, UE A1 and UE B1 are located in the center of AN A'scoverage and AN B's coverage, respectively, so they may be called ascenter UEs. UE A2 and UE B2 are located in the edge of respectivecoverage, and thus may be called as edge UEs.

According to the present disclosure, high carrier sensing thresholds areapplied to the center UEs, and low carrier sensing thresholds areapplied to the edge UEs. Please be noted that the terms “high” and “low”here are relative with respect to each other. For example, as comparedto a carrier sensing threshold for UE A2, a higher one may be applied toUE A1.

The carrier sensing threshold can be adapted to determine the channelavailability.

For example, the carrier sensing threshold may be dynamically derivedbased on a predefined mapping table (see Table 1 below) between themeasured geometry and the absolute carrier sensing threshold value. Thenthe radio node may determine the channel availability by comparing themeasured geometry to the determined absolute carrier sensing threshold:

TABLE 1 geometry to carrier sensing threshold mapping table Carriersensing threshold Condition (Th_(ad)) Measured geometry <= low lowcarrier sensing threshold threshold Measured geometry > low high carriersensing threshold threshold

On exemplary rule to determine the channel availability is as follows:

-   -   If L_(A)≤Th_(ad), channel is determined to be available, wherein        L_(A) refers to the geometry;    -   Else, channel is determined to be busy.

The method 300 may be also applied in a UE, such as UE1 as shown in FIG.1.

FIG. 6 schematically illustrates a method 600 used in a UE according toembodiments of the present disclosure. It is assumed that the UE is totransmit data to its serving radio node over a radio frequency band.Here, the radio frequency band refers to one or more radio frequencysub-bands or one or more carriers implemented by one or more antennas.

At step S610, the UE obtains a network geometry of the UE with respectto a coverage served by the radio node. This may be done in variouswell-known manners in the art.

In an implementation, the network geometry includes location of the UEin the coverage. Furthermore, the location of the UE in the coverage maybe characterized by a pilot signal quality of the radio node. The pilotsignal quality of the radio node is indicated by one of: a referencesignal strength of the radio node; a reference signal SINR of the radionode; or a reference signal strength of the radio node and referencesignal strength of one or more neighboring radio nodes of the radionode.

At step S620, the UE determines a carrier sensing threshold for the UEbased on the network geometry. The carrier sensing threshold is used forLBT measurement over a radio frequency band applicable for transmittingdata to the radio node.

In an implementation, the carrier sensing threshold may be adjusted tobe larger if the UE moves towards the center of the coverage.Alternatively, the carrier sensing threshold may be adjusted to besmaller if the UE moves towards the edge of the coverage.

At step S630, the UE applies the carrier sensing threshold in the LBTmeasurement. This step is similar to step S330.

For example, step S630 may include steps S631, S632, and S633 asillustrated in FIG. 7.

At step S631, the UE measures a radio frequency signal power level onthe radio frequency band. Conventionally, before such a measuring, theUE may listen to the radio frequency band periodically or in a fixedinterval. This step is similar to step S331.

At step S632, the UE compares the measured radio frequency signal powerlevel with the carrier sensing threshold.

If the radio frequency signal power level is smaller than or equal tothe carrier sensing threshold (“Y” branch in FIG. 7), this means thatthe radio frequency band is available currently. Then, the flowchartproceeds to step S633, where the UE determines that the radio frequencyband is available for transmitting data to its serving radio node. Inthis case, the method 600 proceeds to step S640.

At step S640, the UE transmits data to the radio node over the radiofrequency band.

If the radio frequency signal power level is larger than the carriersensing threshold (“N” branch in FIG. 7), this means that the radiofrequency band is being occupied, e.g., by other UEs or radio nodes. Inthis case, the flowchart goes back to step S631 i.e., to continue withthe LBT measurement again.

The present disclosure further proposes to adapt a width of the RX beamfor a radio node according to the network geometry.

With high gain beamforming, the highest beamforming gain can only beachieved when the RX beam of the receiver well targets to thetransmitter and the TX beam of the transmitter well targets to thereceiver.

FIG. 8 illustrates exemplary wireless systems in which high gainbeamforming is applied. The left part of FIG. 8 shows that the TX beamand RX beam are well matched and maximum beamforming gain can beachieved. The right part of FIG. 8 shows that the TX beam and RX beamare not matched and the sub-optimal beamforming gain is achieved. Insome cases, the beamforming gain could be even lower than using wider TXand RX beams due to only side lobe reaches the incoming direction of theRX beam.

Deafness could occur in the wireless systems with high gain beamformingas shown in FIG. 8. For instance, the receiver may not hear thetransmitter when there is a large mismatch between the RX beam of thereceiver and the TX beam of the transmitter. The deafness probabilitybecomes higher when the TX beam and/or the RX beam are narrower.

To mitigate such deafness by using the TX and/or RX beam sweepingresults in large overhead and considerable delay for the subsequent datatransmission, the present disclosure propose to conditionally determinethe RX beam according to the network geometry. To be specific, thepresent disclosure proposes to adapt the RX beam's width based on thenetwork geometry.

FIG. 9 schematically illustrates a method 900 used in a radio nodeaccording to embodiments of the present disclosure. It is assumed thatthe radio node is to transmit data to a UE served by the radio node overa radio frequency band.

At step S910, the radio node obtains a network geometry of the UE withrespect to a coverage served by the radio node. This may be done invarious well-known manners in the art.

In an implementation, the network geometry includes location of the UEin the coverage. Furthermore, the location of the UE in the coverage maybe characterized by a pilot signal quality of the radio node. The pilotsignal quality of the radio node is indicated by one of: a referencesignal strength of the radio node; a reference signal SINR of the radionode; or a reference signal strength of the radio node and referencesignal strength of one or more neighboring radio nodes of the radionode.

At step S920, the radio node determines a width of a RX beam based onthe network geometry. The RX beam is used for LBT measurement over aradio frequency band applicable for transmitting data to the UE.

In an implementation, the width of the RX beam may be adjusted to bewider if the UE moves towards the center of the coverage. Alternatively,the width of the RX beam may be adjusted to be narrower if the UE movestowards the edge of the coverage.

At step S930, the radio node applies the RX beam with the determinedwidth in the LBT measurement.

In an implementation, step S930 may include steps S931, S932, S933 andS934 as illustrated in FIG. 10.

At step S931, the radio node listens to the radio frequency band, byusing a RX beam.

At step S932, the radio node measures a radio frequency signal powerlevel on the radio frequency band.

At step S933, the radio node compares the measured radio frequencysignal power level with a predetermined carrier sensing threshold. Thepredetermined carrier sensing threshold may be determined by the radionode in various manners.

For example, the predetermined carrier sensing threshold may bedetermined as done in the method 300. Alternatively, the predeterminedcarrier sensing threshold may be configured by the radio node in advanceand keeps fixed for different UEs. If the radio frequency signal powerlevel is smaller than or equal to the predetermined carrier sensingthreshold (“Y” branch in FIG. 10), this means that the radio frequencyband is available currently. Then, the flowchart proceeds to step S934,where the radio node determines that the radio frequency band isavailable for transmitting data to the UE. In this case, the method 900proceeds to step S940.

At step S940, the radio node transmits data to the UE over the radiofrequency band.

If the radio frequency signal power level is larger than thepredetermined carrier sensing threshold (“N” branch in FIG. 10), thismeans that the radio frequency band is being occupied, e.g., by otherradio nodes. In this case, the flowchart goes back to step S931 tocontinue with the LBT measurement again.

With the method 900, the present disclosure can relieve the deafnessproblem brought by the use of high gain beamforming.

Furthermore, adapting the RX beam width can also avoid the overhead ofbeam forming training. To be specific, wide TX and/or RX beam can beused for a data block, whose block size is smaller than a predeterminedthreshold or whose channel occupation time is shorter than anotherpredetermined threshold.

FIG. 11 illustrates one exemplary scenario showing how to adapt RX beamsaccording to the network geometry according to embodiments of thepresent disclosure.

As shown in FIG. 11, UE A1 and UE B1 are located in the center of AN A'scoverage and AN B's coverage, respectively, so they may be called ascenter UEs. UE A2 and UE B2 are located in the edge of respectivecoverage, and thus may be called as edge UEs.

According to the present disclosure, wide RX beams are applied to theUEs close to the center of the coverage, and narrow carrier sensingthresholds are applied to the UEs close to the edge of the coverage.Please be noted that the terms “wide” and “narrow” here are relativewith respect to each other. For example, as compared to a RX beam for UEA2, a wider one may be applied to UE A1.

Similarly, a mapping table like Table 1 may be predefined to dynamicallyderive the RX beams. For example, such a table may be defined betweenthe measured network geometry and the absolute RX beams.

FIG. 12 is a schematic block diagram of a radio node 1200 according toembodiments of the present disclosure. The radio node 1200 serves one ormore UEs which are connected to the radio node via one or more links, ina coverage area. For example, the radio node 1200 may be AN A as shownin FIG. 5, which serves UE A1 and UE A2.

As shown in FIG. 12. The radio node 1200 comprises an obtaining unit1210, a determining unit 1220, a LBT measurement unit 1230, and atransmitting unit 1240. The transmitting unit 1240 is optional.

The obtaining unit 1210 is configured to obtain a network geometry ofthe UE with respect to a coverage served by the radio node. This may bedone in various well-known manners in the art.

In an implementation, the network geometry includes location of the UEin the coverage. Furthermore, the location of the UE in the coverage maybe characterized by a pilot signal quality of the radio node. The pilotsignal quality of the radio node is indicated by one of: a referencesignal strength of the radio node; a reference signal SINR of the radionode; or a reference signal strength of the radio node and referencesignal strength of one or more neighboring radio nodes of the radionode.

The determining unit 1220 is configured to determine a carrier sensingthreshold for the UE based on the network geometry. The carrier sensingthreshold is used for LBT measurement over a radio frequency bandapplicable for transmitting data to the UE.

In an implementation, the determining unit 1220 may adjust the carriersensing threshold to be larger if the UE moves towards the center of thecoverage. Alternatively, the determining unit 1220 may adjust thecarrier sensing threshold to be smaller if the UE moves towards the edgeof the coverage. This is illustrated in FIG. 5 by way of an example.

The LBT measurement unit 1230 is configured to apply the carrier sensingthreshold in the LBT measurement.

In an implementation, the LBT measurement unit 1230 is furtherconfigured to: measure a radio frequency signal power level on the radiofrequency band; and determine that the radio frequency band is availablefor transmitting data to the UE if the radio frequency signal powerlevel is smaller than or equal to the carrier sensing.

The transmitting unit 1240 is configured to transmit data to the UE overthe radio frequency band when the radio frequency band is available fortransmitting data to the UE.

It should be noted that two or more different units in this disclosuremay be logically or physically combined. For example, the obtaining unit1210 and the determining unit 1220 may be combined as one single unit,e.g., a processor in the radio node.

The radio node 1200 may be also embodied on a radio node comprising atransceiver, a processor and a memory. The memory contains instructionsexecutable by the processor whereby the radio node is operative toperform the method 300.

FIG. 13 is a schematic block diagram of a UE 1300 according toembodiments of the present disclosure. The UE 1300 is served by a radionode, which serves one or more UEs which are connected to the radio nodevia one or more links, in a coverage area. For example, UE 1300 may beUE A1 as shown in FIG. 5, which is served by AN A.

As shown in FIG. 13. The UE 1300 comprises an obtaining unit 1310, adetermining unit 1320, a LBT measurement unit 1330, and a transmittingunit 1340. The transmitting unit 1340 is optional.

The obtaining unit 1310 is configured to obtain a network geometry ofthe UE with respect to a coverage served by the radio node. This may bedone in various well-known manners in the art.

In an implementation, the network geometry includes location of the UEin the coverage. Furthermore, the location of the UE in the coverage maybe characterized by a pilot signal quality of the radio node. The pilotsignal quality of the radio node is indicated by one of: a referencesignal strength of the radio node; a reference signal SINR of the radionode; or a reference signal strength of the radio node and referencesignal strength of one or more neighboring radio nodes of the radionode.

The determining unit 1320 is configured to determine a carrier sensingthreshold for the UE based on the network geometry. The carrier sensingthreshold is used for LBT measurement over a radio frequency bandapplicable for transmitting data to the radio node.

In an implementation, the determining unit 1320 may adjust the carriersensing threshold to be larger if the UE moves towards the center of thecoverage. Alternatively, the determining unit 1320 may adjust thecarrier sensing threshold to be smaller if the UE moves towards the edgeof the coverage. This is illustrated in FIG. 5 by way of an example.

The LBT measurement unit 1330 is configured to apply the carrier sensingthreshold in the LBT measurement.

In an implementation, the LBT measurement unit 1330 is furtherconfigured to: measure a radio frequency signal power level on the radiofrequency band; and determine that the radio frequency band is availablefor transmitting data to the radio node if the radio frequency signalpower level is smaller than or equal to the carrier sensing threshold.

The transmitting unit 1340 is configured to transmit data to the radionode over the radio frequency band when the radio frequency band isavailable for transmitting data to the UE.

It should be noted that two or more different units in this disclosuremay be logically or physically combined. For example, the obtaining unit1310 and the determining unit 1320 may be combined as one single unit,e.g., a processor in the UE.

The UE 1300 may be also embodied on a UE comprising a transceiver, aprocessor and a memory. The memory contains instructions executable bythe processor whereby the UE is operative to perform the method 600.

FIG. 14 is a schematic block diagram of a radio node 1400 according toembodiments of the present disclosure. The radio node 1400 serves one ormore UEs which are connected to the radio node via one or more links, ina coverage area. For example, the radio node 1400 may be AN A as shownin FIG. 11, which serves UE A1 and UE A2.

As shown in FIG. 14. The radio node 1400 comprises an obtaining unit1410, a determining unit 1420, a LBT measurement unit 1430, and atransmitting unit 1440. The transmitting unit 1440 is optional.

The obtaining unit 1410 is configured to obtain a network geometry ofthe UE with respect to a coverage served by the radio node. This may bedone in various well-known manners in the art.

In an implementation, the network geometry includes location of the UEin the coverage. Furthermore, the location of the UE in the coverage maybe characterized by a pilot signal quality of the radio node. The pilotsignal quality of the radio node is indicated by one of: a referencesignal strength of the radio node; a reference signal SINR of the radionode; or a reference signal strength of the radio node and referencesignal strength of one or more neighboring radio nodes of the radionode.

The determining unit 1420 is configured to determine a width of a RXbeam based on the network geometry. The RX beam is used for LBTmeasurement over a radio frequency band applicable for transmitting datato the UE.

In an implementation, the determining unit 1420 may adjust the width tobe wider if the UE moves towards the center of the coverage.Alternatively, the determining unit 1420 may adjust the width to benarrower if the UE moves towards the edge of the coverage. This isillustrated in FIG. 11 by way of an example.

The LBT measurement unit 1430 is configured to apply the RX beam withthe determined width in the LBT measurement.

In an implementation, the LBT measurement unit 1430 is furtherconfigured to: listen to the radio frequency band, by using the RX beam;measure a radio frequency signal power level on the radio frequencyband; and determine that the radio frequency band is available fortransmitting data to the UE if the radio frequency signal power level issmaller than or equal to a predetermined carrier sensing threshold.

The transmitting unit 1440 is configured to transmit data to the UE overthe radio frequency band the radio frequency band is available fortransmitting data to the UE.

It should be noted that two or more different units in this disclosuremay be logically or physically combined. For example, the obtaining unit1410 and the determining unit 1420 may be combined as one single unit,e.g., a processor in the radio node.

FIG. 15 schematically shows an embodiment of an arrangement 1500comprising at least one particular computer program product 1508according to a particular embodiment of the present disclosure. Thearrangement 1500 may be used in the radio node 1200, UE 1300, or theradio node 1400 according to the present disclosure. Comprised in thearrangement 1500 are here a processing unit 1506, e.g., with a DigitalSignal Processor (DSP). The processing unit 1506 may be a single unit ora plurality of units to perform different actions of proceduresdescribed herein. The arrangement 1500 may also comprise an input unit1502 for receiving signals from other entities, and an output unit 1504for providing signal(s) to other entities. The input unit and the outputunit may be arranged as an integrated entity or as illustrated in theexample of FIG. 12, FIG. 13, or FIG. 14.

Furthermore, the at least one computer program product 1508 may be inthe form of a non-volatile or volatile memory, e.g., an ElectricallyErasable Programmable Read-Only Memory (EEPROM), a flash memory and ahard drive. The computer program product 1508 comprises a computerprogram 1510, which comprises code/computer readable instructions, whichwhen executed by the processing unit 1506 in the arrangement 1500 causesthe arrangement 1500 and/or the network node or the UE in which it iscomprised to perform the actions, e.g., of the procedure describedearlier in conjunction with either of FIGS. 3, 6 and 9.

The computer program 1510 may be configured as a computer program codestructured in computer program modules 1510A-1510D, 1510E-1510H, or1510I-1510L. Hence, in an exemplifying embodiment when the arrangement1500 is used in the radio node 1200, the code in the computer program ofthe arrangement 1500 includes an obtaining module 1510A, for obtaining anetwork geometry of a UE served by the radio node with respect to acoverage served by the radio node. The code in the computer program 1510further includes a determining module 1510B, for determining a carriersensing threshold for the UE based on the network geometry, the carriersensing threshold for use in Listen-Before-Talk (LBT) measurement over aradio frequency band applicable for transmitting data to the UE. Thecode in the computer program 1510 may further include a LBT measurementmodule 1510C, for applying the carrier sensing threshold in the LBTmeasurement. The code in the computer program 1510 may comprise furthermodules, illustrated as module 1510D, e.g. for controlling andperforming other related procedures associated with the radio node'soperations.

In yet another exemplifying embodiment when the arrangement 1500 is usedin the UE 1300, the code in the computer program of the arrangement 1500includes an obtaining module 1510E, for obtaining a network geometry ofa UE served by the radio node with respect to a coverage served by theradio node. The code in the computer program 1510 further includes adetermining module 1510F, for determining a carrier sensing thresholdfor the UE based on the network geometry, the carrier sensing thresholdfor use in Listen-Before-Talk (LBT) measurement over a radio frequencyband applicable for transmitting data to the radio node. The code in thecomputer program 1510 may further include a LBT measurement module1510G, for applying the carrier sensing threshold in the LBTmeasurement.

The code in the computer program 1510 may comprise further modules,illustrated as module 1510H, e.g. for controlling and performing otherrelated procedures associated with the UE's operations.

In another exemplifying embodiment when the arrangement 1500 is used inthe radio node 1400, the code in the computer program of the arrangement1500 includes an obtaining module 1510I, for obtaining a networkgeometry of a UE served by the radio node with respect to a coverageserved by the radio node. The code in the computer program 1510 furtherincludes a determining module 1510J, for determining a width of a RXbeam based on the network geometry, the RX beam for use inListen-Before-Talk (LBT) measurement over a radio frequency bandapplicable for transmitting data to the UE. The code in the computerprogram 1510 may further include a LBT measurement module 1510K, forapplying the RX beam with the determined width in the LBT measurement.The code in the computer program 1510 may comprise further modules,illustrated as module 1510L, e.g. for controlling and performing otherrelated procedures associated with the radio node's operations.

The computer program modules could essentially perform the actions ofthe flow illustrated in FIG. 3, to emulate the radio node 1200, or theactions of the flow illustrated in FIG. 6, to emulate the UE 1300, orthe actions of the flow illustrated in FIG. 9 to emulate the radio node1400. In other words, when the different computer program modules areexecuted in the processing unit 1506, they may correspond, e.g., to theunits 1210-1230 of FIG. 12, or to the units 1310-1330 of FIG. 13, or tothe units 1410-1430 of FIG. 14.

Although the code means in the embodiments disclosed above inconjunction with FIG. 15 are implemented as computer program moduleswhich when executed in the processing unit causes the device to performthe actions described above in conjunction with the figures mentionedabove, at least one of the code means may in alternative embodiments beimplemented at least partly as hardware circuits.

The processor may be a single CPU (Central processing unit), but couldalso comprise two or more processing units. For example, the processormay include general purpose microprocessors; instruction set processorsand/or related chips sets and/or special purpose microprocessors such asApplication Specific Integrated Circuit (ASICs). The processor may alsocomprise board memory for caching purposes. The computer program may becarried by a computer program product connected to the processor. Thecomputer program product may comprise a computer readable medium onwhich the computer program is stored. For example, the computer programproduct may be a flash memory, a Random-access memory (RAM), a Read-OnlyMemory (ROM), or an EEPROM, and the computer program modules describedabove could in alternative embodiments be distributed on differentcomputer program products in the form of memories within the UE.

The present disclosure is described above with reference to theembodiments thereof. However, those embodiments are provided just forillustrative purpose, rather than limiting the present disclosure. Thescope of the disclosure is defined by the attached claims as well asequivalents thereof. Those skilled in the art can make variousalternations and modifications without departing from the scope of thedisclosure, which all fall into the scope of the disclosure.

The invention claimed is:
 1. A method used in a radio node, the methodcomprising: obtaining a network geometry of a User Equipment (UE) servedby the radio node with respect to a coverage served by the radio node,wherein the network geometry indicates locality of the UE in thecoverage, and wherein the locality of the UE in the coverage ischaracterized by a single value measuring a power level differencebetween a first power level received from the radio node and a secondpower level received from a neighboring radio node that provides themaximum power level among a set of neighboring radio nodes; selecting acarrier sensing threshold from a plurality of carrier sensing thresholdsfor the UE based on the network geometry, the carrier sensing thresholdfor use in Listen-Before-Talk (LBT) measurement over a radio frequencyband applicable for transmitting data to the UE, wherein each ofplurality of carrier sensing thresholds is a receiving power thresholdand maps to a network geometry range; and applying the carrier sensingthreshold in the LBT measurement.
 2. The method according to claim 1,wherein applying the carrier sensing threshold in the LBT measurementcomprises: measuring a radio frequency signal power level on the radiofrequency band; and determining that the radio frequency band isavailable for transmitting data to the UE if the radio frequency signalpower level is smaller than or equal to the carrier sensing threshold,and wherein the method further comprises: transmitting data to the UEover the radio frequency band.
 3. The method according to claim 1,wherein determining the carrier sensing threshold for the UE based onthe network geometry comprises: adjusting the carrier sensing thresholdto be larger if the UE moves towards the center of the coverage; and/oradjusting the carrier sensing threshold to be smaller if the UE movestowards the edge of the coverage.
 4. The method according to claim 1,wherein the locality of the UE in the coverage is further characterizedby a pilot signal quality of the radio node, and wherein the pilotsignal quality of the radio node is indicated by one of: a referencesignal strength of the radio node; a reference signal Signal toInterference plus Noise Ratio (SINR) of the radio node; and a referencesignal strength of the radio node and reference signal strength of oneor more neighboring radio nodes of the radio node.
 5. A method used in aUser Equipment (UE) served by a radio node, the method comprising:obtaining a network geometry of the UE with respect to a coverage servedby the radio node, wherein the network geometry indicates locality ofthe UE in the coverage, and wherein the locality of the UE in thecoverage is characterized by a single value measuring a power leveldifference between a first power level received from the radio node anda second power level received from the neighboring radio node thatprovides the maximum power level among a set of neighboring radio nodes;selecting a carrier sensing threshold from a plurality of carriersensing thresholds for the UE based on the network geometry, the carriersensing threshold for use in Listen-Before-Talk (LBT) measurement over aradio frequency band applicable for transmitting data to the radio node,wherein each of plurality of carrier sensing thresholds is a receivingpower threshold and maps to a network geometry range; and applying thecarrier sensing threshold in the LBT measurement.
 6. The methodaccording to claim 5, wherein applying the carrier sensing threshold inthe LBT measurement comprises: measuring a radio frequency signal powerlevel on the radio frequency band; and determining that the radiofrequency band is available for transmitting data to the radio node ifthe radio frequency signal power level is smaller than or equal to thecarrier sensing threshold, and wherein the method further comprises:transmitting data to the radio node over the radio frequency band. 7.The method according to claim 5, wherein determining the carrier sensingthreshold for the UE based on the network geometry comprises: adjustingthe carrier sensing threshold to be larger if the UE moves towards thecenter of the coverage; and/or adjusting the carrier sensing thresholdto be smaller if the UE moves towards the edge of the coverage.
 8. Themethod according to claim 5, wherein the pilot signal quality of theradio node is indicated by one of: a reference signal strength of theradio node; a reference signal Signal to Interference plus Noise Ratio(SINR) of the radio node; and a reference signal strength of the radionode and reference signal strength of one or more neighboring radionodes of the radio node.
 9. A radio node, comprising: a processor and anon-transitory computer readable medium containing instructions, whichwhen executed by the processor, causing the radio node to: obtain anetwork geometry of a User Equipment (UE) served by the radio node withrespect to a coverage served by the radio node, wherein the networkgeometry indicates locality of the UE in the coverage, and wherein thelocality of the UE in the coverage is characterized by a single valuemeasuring a power level difference between a first power levels receivedfrom the radio node and a second power level received from a neighboringradio node that provides the maximum power level among a set ofneighboring radio nodes, select a carrier sensing threshold from aplurality of carrier sensing thresholds for the UE based on the networkgeometry, the carrier sensing threshold for use in Listen-Before-Talk(LBT) measurement over a radio frequency band applicable fortransmitting data to the UE, wherein each of plurality of carriersensing thresholds is a receiving power threshold and maps to a networkgeometry range, and apply the carrier sensing threshold in the LBTmeasurement.
 10. The radio node according to claim 9, further to:measure a radio frequency signal power level on the radio frequencyband, determine that the radio frequency band is available fortransmitting data to the UE if the radio frequency signal power level issmaller than or equal to the carrier sensing, and transmit data to theUE over the radio frequency band.
 11. The radio node according to claim9, further to: adjust the carrier sensing threshold to be larger if theUE moves towards the center of the coverage; and/or adjust the carriersensing threshold to be smaller if the UE moves towards the edge of thecoverage.
 12. The radio node according to claim 9, wherein the localityof the UE in the coverage is further characterized by a pilot signalquality of the radio node, and wherein the pilot signal quality of theradio node is indicated by one of: a reference signal strength of theradio node; a reference signal Signal to Interference plus Noise Ratio(SINR) of the radio node; and a reference signal strength of the radionode and reference signal strength of one or more neighboring radionodes of the radio node.
 13. A User Equipment (UE) served by a radionode, the UE comprising: a processor and a non-transitory computerreadable medium containing instructions, which when executed by theprocessor, causing the UE to: obtain a network geometry of the UE withrespect to a coverage served by the radio node, wherein the networkgeometry indicates locality of the UE in the coverage, and wherein thelocality of the UE in the coverage is characterized by a single valuemeasuring a power level difference between a first power levels receivedfrom the radio node and a second power level received from a neighboringradio node that provides the maximum power level among a set ofneighboring radio nodes, select a carrier sensing threshold from aplurality of carrier sensing thresholds for the UE based on the networkgeometry, the carrier sensing threshold for use in Listen-Before-Talk(LBT) measurement over a radio frequency band applicable fortransmitting data to the radio node, wherein each of plurality ofcarrier sensing thresholds is a receiving power threshold and maps to anetwork geometry range, and apply the carrier sensing threshold in theLBT measurement.
 14. The UE according to claim 13, further to: measure aradio frequency signal power level on the radio frequency band,determine that the radio frequency band is available for transmittingdata to the radio node if the radio frequency signal power level issmaller than or equal to the carrier sensing threshold, and transmitdata to the radio node over the radio frequency band.
 15. The UEaccording to claim 13, wherein the UE is further to: adjust the carriersensing threshold to be larger if the UE moves towards the center of thecoverage; and/or adjust the carrier sensing threshold to be smaller ifthe UE moves towards the edge of the coverage.
 16. The UE according toclaim 13, wherein the locality of the UE in the coverage is furthercharacterized by a pilot signal quality of the radio node, and whereinthe pilot signal quality of the radio node is indicated by one of: areference signal strength of the radio node; a reference signal Signalto Interference plus Noise Ratio (SINR) of the radio node; and areference signal strength of the radio node and reference signalstrength of one or more neighboring radio nodes of the radio node.